1. Field of the Invention
The present invention relates to a display device, and in particular, to a display device comprising a mesh structure.
2. Description of the Related Art
Matrix driven display devices, which are presently widely used, are each formed as a matrix structure in which elements and wires are stacked on a support substrate such as a glass substrate. For example, in a passive matrix type liquid crystal display device, a silicon oxide film is formed on the glass substrate using a plasma enhanced chemical deposition method (PECVD), in order to prevent alkali elution. Subsequently, transparent electrodes consisting of a composite oxide of indium and tin (ITO) are formed on the silicon oxide film using a sputtering method or the like. Then, the transparent electrode layer is machined into a desired stripe shape using, for example, a photo-etching method. Further, for example, in a passive selfluminous display device having a selfluminous characteristic in which an organic material that exhibits electroluminescence (OLED) is used as a light emitting member, a film forming process and a photo-etching process are used to form a wiring structure constituting a matrix, on a glass substrate, as in the case of a passive liquid crystal display device. In this case, the glass substrate is present in order to support the wiring structure during the process or after a device has been formed. This is the only function of the glass substrate.
Thus, for display devices, a method of using a film forming process and a photo-etching process are mostly used to form wiring constituting a matrix, on a support substrate. Accordingly, the matrix structure presently used is formed by sequentially and repeatedly executing formation, machining, and the like of functional films starting at a position close to the substrate.
Jpn. Pat. Appln. KOKAI Publication No. 2002-184580 discloses the structure of a fibrous light source. However, in the fibrous light source, the emission of light by fibers is utilized and the fibers are arranged in coil form to construct an illuminating light source with a large area.
If the deposition of materials and the machining of films are sequentially executed starting at a position close to the substrate as described above, then the following problems may occur: the functions of the device are dominated by the support substrate, the wiring function is limited, the size of the display device is limited during design, and a large number of relevant members are consumed.
First, a function of the display device, particularly its shape, depends significantly on the support substrate. Typically, the glass substrate used in the display device has a thickness of, for example, 0.7 mm. If liquid crystal is used for display, a part of the display device which exhibits its function has a thickness of at most about 10 μm. However, the glass substrate accounts for most of the thickness of the display device. Further, in connection with a function of the display device, it may be desirable to make a display device flexible. However, with the glass substrate, it is difficult to make the display portion sufficiently flexible owing to the rigidity of glass. Thus, a plastic substrate, which is more flexible than the glass substrate, may be used in order to realize sufficient flexibility. However, even the plastic substrate may pose problems during the formation of a display device. For example, it is difficult to use a temperature process executed at at least 200° C. and the thickness must be, for example, at least 0.1 mm in order to ensure supportability during manufacture.
Further, when wiring is formed on the support substrate, a physical or chemical deposition method is mostly used to form desired metal and conductive composite oxides into thin film layers. On this occasion, for example, in order to ensure a sufficient charge transfer for the wiring, a technique for increasing the thickness during deposition is used. However, in view of productivity and for the purpose of preventing structural destruction caused by stress, the thickness is limited to at most 1 μm. This prevents a sufficient resistance cross section from being obtained. Consequently, display devices requiring a large current, a large area, or the like are limited by the performance of the wiring.
If the deposition of thin films and the photo-etching process are executed on the support substrate, the whole display device or a combination of display devices must be formed into a matrix structure. Thus, the size, fineness, and the like of the display device are determined in its design stage. This limits the degree of freedom during manufacture. That is, an intermediate device formed on the support substrate and including wiring is adaptable only to an initially designed display device. It is impossible to subsequently make an arbitrary change in display area or the like.
Moreover, if the deposition of thin films and the photo-etching process are executed on the support substrate, then disadvantageously a large number of consumable members are used, which are not left in the completed display device. For example, when wiring is formed, a thin film is deposited almost all over the surface of the support substrate, that is, in both parts of the substrate which require the wiring and those which do not require the wiring. In this case, the parts not requiring the wiring are removed by the etching process as unwanted members. Further, for the purpose of achieving this etching process, machining is carried out using a photo process with a photosensitive resin or the like. In this case, the photosensitive resin or the like is also removed as an unwanted member after the machining. A large number of these consumable members contribute to increasing the cost of the display device. Further, many of these consumable members may affect the global environments. Therefore, the amounts of such consumable members used must be reduced.